1. Field of the Invention
The present invention is directed to the composition, methods of preparation and uses novel cucurbituril derivatives having various repeating units and cavities of various sizes.
2. Description of the Related Art
Cucurbituril is a macrocyclic compound whose preparation was first reported by Behrend et al. in 1905 (Liebigs Ann. Chem. 1905, 339, 1). According to their report, the condensation of glycoluril and excess formaldehyde in the presence of hydrochloric acid (HCl) produces an amorphous solid. Dissolution of the solid in hot concentrated sulfuric acid, dilution of the solution with water followed by slow cooling of the solution to room temperature produces a crystalline material. They wrongly characterized this substance as C10H11N7O4.2H2O solely based on elemental analysis. In 1981, this substance was rediscovered by Mock and coworkers (J. Am. Chem. Soc., 1981, 103, 7367). They correctly characterized it as a hexameric macrocyclic compound with composition of C36H36,N24O12, which was also confirmed by X-ray crystal structure determination. They named it cucurbituril which we from now on refer to as cucurbit[6]uril.
Since then an improved preparation procedure for cucurbit[6]uril has been disclosed (DE 196 03 377 A1). According to this new procedure, in the presence of an acid, glycoluril and formaldehyde are reacted at 100° C. or a higher temperature, and then the reaction mixture is further heated up to 150° C. to concentrate the reaction mixture. Cooling the mixture to room temperature results in cucurbit[6]uril. This synthetic method can increase the yield of cucurbit[6]uril. However, it was reported to produce only the hexameric cucurbituril, cucurbit[6]uril, with improved yield. The cucurbituril derivatives having less or more than six monomers cannot be synthesized by the method. Moreover, the synthetic method requires a much higher reaction temperature, which makes it less practical.
In addition, decamethylcucurbit[5]uril, in which five dimethanodimethylglycoluril units form a cyclic structure by the condensation of dimethylglycoluril and formaldehyde, has been reported (Angew. Chem. Int. Ed. Engl. 1992, 31, 1475).
As described above, up to now, only two cucurbituril derivatives, cucurbit[n]uril with n=6 and decamethylcucurbit[n]uril with n=5, have been reported. The known cucurbituril derivatives are very limited in terms of types and cavity sizes (5.5 or less). Also, they are insoluble in common solvents such as water or methanol, and thus their applications are limited.